CA1165868A - Method and apparatus for correcting automatically the designation of type of tape carrier - Google Patents
Method and apparatus for correcting automatically the designation of type of tape carrierInfo
- Publication number
- CA1165868A CA1165868A CA000342508A CA342508A CA1165868A CA 1165868 A CA1165868 A CA 1165868A CA 000342508 A CA000342508 A CA 000342508A CA 342508 A CA342508 A CA 342508A CA 1165868 A CA1165868 A CA 1165868A
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- CA
- Canada
- Prior art keywords
- tape
- cassette
- type
- reel
- display
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
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- 238000010586 diagram Methods 0.000 description 6
- 238000012546 transfer Methods 0.000 description 5
- 230000002035 prolonged effect Effects 0.000 description 3
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- 238000000429 assembly Methods 0.000 description 2
- 230000000712 assembly Effects 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 238000004804 winding Methods 0.000 description 2
- 241000725101 Clea Species 0.000 description 1
- QCDFBFJGMNKBDO-UHFFFAOYSA-N Clioquinol Chemical class C1=CN=C2C(O)=C(I)C=C(Cl)C2=C1 QCDFBFJGMNKBDO-UHFFFAOYSA-N 0.000 description 1
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- 238000002474 experimental method Methods 0.000 description 1
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- XLNZEKHULJKQBA-UHFFFAOYSA-N terbufos Chemical compound CCOP(=S)(OCC)SCSC(C)(C)C XLNZEKHULJKQBA-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B27/00—Editing; Indexing; Addressing; Timing or synchronising; Monitoring; Measuring tape travel
- G11B27/10—Indexing; Addressing; Timing or synchronising; Measuring tape travel
- G11B27/11—Indexing; Addressing; Timing or synchronising; Measuring tape travel by using information not detectable on the record carrier
- G11B27/13—Indexing; Addressing; Timing or synchronising; Measuring tape travel by using information not detectable on the record carrier the information being derived from movement of the record carrier, e.g. using tachometer
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B27/00—Editing; Indexing; Addressing; Timing or synchronising; Monitoring; Measuring tape travel
- G11B27/10—Indexing; Addressing; Timing or synchronising; Measuring tape travel
- G11B27/34—Indicating arrangements
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B2220/00—Record carriers by type
- G11B2220/90—Tape-like record carriers
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B27/00—Editing; Indexing; Addressing; Timing or synchronising; Monitoring; Measuring tape travel
- G11B27/36—Monitoring, i.e. supervising the progress of recording or reproducing
Landscapes
- Indexing, Searching, Synchronizing, And The Amount Of Synchronization Travel Of Record Carriers (AREA)
- Automatic Tape Cassette Changers (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
Method and apparatus for determining automatically the type of tape carrier introduced into a device designed for transferring a tape between two reels. Two positions of the tape are compared and a signal is generated which is representative of this comparison. The comparison signal is compared with an interval or a reference value and as a result of this latter comparison, the indication of the type of tape carrier is either corrected or not corrected.
Method and apparatus for determining automatically the type of tape carrier introduced into a device designed for transferring a tape between two reels. Two positions of the tape are compared and a signal is generated which is representative of this comparison. The comparison signal is compared with an interval or a reference value and as a result of this latter comparison, the indication of the type of tape carrier is either corrected or not corrected.
Description
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` ` Description o~ the Inven~ion _ _ __ . ___ rL~Ie presenl: invent:ion relates to improvel~nts in m~thc~s and apparatus for inclica-ting the rx,sition of a fleYibl~ w~b being transferred from one ree] to a second reel in a ~eb/reel assen~ly, and more particularly concerns tape transport apparatus for tape casse-ttes and the determination of whether or not the type of cassette selected or inclicated is correct so that valid position information may be provided for the tape.
In U.S. Patent No. 4,172,231, commonly assigned with the present application, a me-thod and apparatus is illustrated which provides precise indications of the position of a tape during its transfer from a supply reel to a take up reel.
According to the teachings of the above mentioned patent, the rotational speeds of a supply reel and a take up reel are measured, and the ratio between these measurements is established independently of the speed and the direction of movement of the tape. Reference data in the form of constants representing the characteristics of different types of reels and tapes, such as specific cassette type identifications, are stored in the device, and the reference data or constants corresponding to the reels and tape in use are manually selected and are utilized in calculations. Intermediate signals representing the ratio between the rotational speeds of the supply reel and the take up reel are generated, and with the aid o these intermediate signals and of the reference data or constants, output slgnals are produced as a function of the instantaneous position of the tape with respect to one and/or the other of one of its ends. The output signals are used for indicating the position of the tape and/or for controlling certain operations of the tape device.
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~ he manua] se:Lec-tLon of cons~ants correspondincJ
to the t~pe of casset-te uged lnvolves ~he clan~er of a u~er selectiny the wrong cassette -type. Irhis rnay lea~l to ~aul-t~
indication of tape position, and a-t hiyh speeds prema-ture slowing down wi-th unnecessary increase in winding and unwinding times, or even no slowiny do~n at the end of the tape with consequent danger of tape breakage and so on.
The invention of the aforesaid U.S. Patent No. 4,172, 231 is described therein as useful in transport apparatus for reel/web assemblies the physical parameters of which are known, the physical parameters including the tape length and thickness, and the reel hub diameters. In such a transport apparatus operating with a web/reel assembly having known physical parameters, the position relative to one end of the web of an intermediate portion being transferred from one reel to the other, may be determined by a computational process using mathematical equations, i.e. by following tape position determination algorithms employing constants established by the known physical parameters of that reel/web assembly, and a ~ariable parameter; namely, the ratio of rotational speeds of the two reels at the intermediate web portion is being transferred from one reel to the other, which ratio continuously csm/~
.
~ 3 ~ f; ~3 changes as the web is transfer~ed. It is explained in saia prior patent that the same algorithms employing the same constants may be followed to determine the position o~ an intermediate web portion at any stage of transfer of the web the only input required at any ~tage is the ratio of the rotational speeds of the reels. By determining tape position in a regularly repea~ing cycle, using said tape positio~
determination algorithms, and producing each cycle an output signal representing the position determined for the web during that cycle, the output signals may be utilized to monitor the transfer of the web in the apparatus, for example, by displaying the continuously changing position of the web or controlling the operation of the transport apparatus.
The method of said prior patent is particularly, although not exclusively, useful in tape transport apparatus for cassettes of tape which are a standard type for example, cassettes providing sixty, ninety and one hundred twenty minutes of playing time known, respectively, as C-60, C-90 and C-120 cassettes. Such cassettes are conventional with two reels and different known lengths and thickness of tape to provide the various lengths of playing time. The method entails first establishing constants for each tape cassette, which constants are used in the position determination algorithms, and storing a set of constants for each tape cassette in, for example, a semiconductor memory unit. In tape transport apparatus under the control of a microprocessor, signals representing the set of constants corresponding to the cassette loaded into the transport apparatus, are recalled from the memory uni~, intermediate signals are generated representing the ratio Pl/P2 measuring the rotational speeds of the reels, and by circuit means such as the microprocessor under program con~rol a determination is made of tape position in terms of the length ~1 or Q 2) or time ttl or t2) to the end of the web on eithar reel of an intermediate portion of the web being .
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transferred from one reel to the other, using positiondetermination algorithms employing the following equations:
Equation (I) Ql A B
1 ~ (P2) (take-up reel) -Equation (I)' Q 2 A
( 2)2 (supply reel) wherein A - L ' T + 1 and B = L
T 1 T2 _ 1 , L representing the total length of magnetic tape, Ql representing the used tape,~ 2~ the remaining tape, T representing the ratio Pl/P2 when L = ~2 i.e. at the beginning of the tape. T is thus a constant which characterizes each type of cassette and which can be determined either mathematically or ~y experiment.
If the two terms of the Equation (I) and (I)' are divided by L, we obtain the following:
With A = A' = T + 1 and B = B' =
L T2 _ 1 L T2 _ 1 E~uation (II) Rl = Al - B! and 1 +~ _\2 ~,P2 1 Equation (II)' R2 = A~ B' L 1 +~ ~ 2 ~ 11 It is also possible to multiply the two terms o~ quation -~: : ' ' ' '', '. ' ' ' ' ; ' ' ' ' ' ':
~.
: ' ~ 165~36~3 II and II' by the duration Z of the cassette, of which the usual types may have the values defined aboveO We then obtain, with-A" = A' x ~ and B " = B' x the followingo Equation (III) tl = A " - B'' 1 + ~P
~P2l Equation (III)' t2 = " ~ B "
Pl Among the other Equations, (I~ and (K)' represent the length of the magnetic tape wound on the take-up reel and on the supply reel respectively, i.e. a position determination in terms of linear dimension. Equations (II) and (II)' represent the ratios of the length of the magnetic tape wound on the take-up reel and on the supply reel respectively to its total length, i.e. a position indication in non-dimensional terms, while Equations (III) and (III)' represent the time taken by th`e magnetic tape to reach the radius Rl on the taXe~up reel and the radius R2 on the supply reel respectively, i.e. a position indication in terms of time, representing the playback time or recording time which has elapsed since the beginning of the magnetic tape or which remains until the end of the magnetic tape respectively~
The sets of constants, A, A'~ ~'', and B, B', B'' for tbe different types of cassettes are determined statistically, so that account can be taken, with sufficient accuracy, of the very slight variations which may exist between different ca~
settes of one and the same type and which result, for example, ..
, ... . . .. . . _ .. . . ~
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:
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from production toler~nces. Cons~arlts ~or the C'~]~0 tar~ casselte have been measured as ~" - 72.2496 and s'' -- 5.996l, as an ex~r~ple of constan-ts for use in web position determination using E~uation III'.
- ~ccording to the rrethod disclosed in said prior patent No.
4,172,231, the rotational speeds of the reels are represented by pulse streams from pulse yenerators driven responsive to rotation of each reel. Pulses at the rate of twenty per revolu-tion of each reel are fed to shift reyisters which accumulate the pulses and reel speed ratios are calculated based on the total number of pulses accumulated in the registers. It was recognized that the accumulated total of pulses in a shift register provided only an approximate representation of the instantaneous rotational speed of one of the reels.
As an improved method over that disclosed in Patent 4,172,231 instantaneous reel speed ratios are calculated based on the real time for each reel to make two revolutions when driven at normal (play or record) speed, and four revolutions when driven at fast (forward or rewind) speed.
For this improved method, pulse genera-tors on the reel spindles produce eight pulses (hereinafter called "reel pulses") each revolution of the reel, which pulses are counted. Clock pulses generated at a rate determined by an internal clock, illustratively 4 KHz, are clocked into and accumulated in a timing reyister for each reel for the time period elapsed until either i6 or 32 reel pulses are counted, the content oE each of the timiny registers then representiny the real time for two or four revolutions of each of the reels; instantaneous reel speed ratios are calculated by dividing the conten-ts of the timing registers.
Further, according to this improved method, an unknown web/reel assembly or cassette is identified by first recalliny from memory predetermined values of constants, which are called I.D. constants, and then proceeding through a '''"'` /?
, '. . ' :.'. ~ . ' ~ ~ B~8 cassette identifying process in which a first tape positio~
determination is made based on the recalled numerical constants, the tape is moved a prescribed distance, a second tape position determination i5 made, the actual prescribed distance is compared with the theoretical distance between the first and second determined positions and in accordance with that comparison, the unknown cassette is determined to be one of the known types, and thus the unknown cassette is identified.
In carrying out the I.D. mode of operation preferably the two positions are determined by operation of a microprocessor under program control using position determination algorithms including one of the equations (I) to (III)' referred to above for computing tape positions employing numerical constants derived from the I.D. constants store, and reel speed ratio i5 measured as the tape is transferred from reel to reel. The two predetermined positions can be selected in arbitrary mannex, and may in particular be fixed by predetermined numbers of revolutions of the reels or pul3es supplied by the rotàtional speed detector or detectors (pulse generators) of one and/or the other of the reels. The process is thus based on measuring the rotational velocity of each of the reels, which velocity is dependent on their characteristics, their state of winding, and the type of tape used.
This method for automatically identifying an unknown cassette as one of a plurality of known types, is implemented in tape transport apparatus operated under the control of a controller that includes a central processor unit (CPU) and associated memory units (ROM) for programs and storage of numerical constants representing the cassettesl and the cassette I~Do constants.
Tape transport apparatus including reel drive motors and motor control circuits thereforl is controlled by the microprocessor type controller to perform the IoDo mode of operation in which .
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the tape is movecl frorn a starti.ng posi-ti.on at no-rr~al sr~ed for -the f;:rcit tape position deterrnination, at fast speed to the .æcond pos:iti.on, at normal speed for -the second tape posi-tion de-termination, and after the cassette is identified, the tape is returned to thc starting position.
m e microprocessor under program control provides means for deterrnining the first and second tape positions, means for calculating the theoretical difference be-tween the first and second posi-tions, means for rneasuring the actual difference between the same positions, means for cornparing -the theoretical and actual differences and in accordance with the comparison confirming tha-t the unknown cassette is of one or of another known t~pe.
In the system descri.bed in the above-rnentioned patent, a display is operated by the controller to display successive tape positions determined by the controller following several revolutions of both ree].s. If such display is updated to show the tape position each such deterrnination, the display may jump 6 to 8 seconds at a time and the jumps may be uneven. In contrast, by the improved method, provi.sion is made for operating such a display so that the display is uniformly and smoothly updated to show changes in tape position. For example, where tape position is displayed -in terms oE t.ime to the end of the tape, the display is operated to show changes in taFe position of one second, the display being operated by a display clock and the rate of the display clock being synchronized wi-th the actual rate of movement of the -tape by comparing-the actual tape position as determined each cycle with the tape position shown on the display, and changing the rate of the display clock to eliminate any diE:Eerence between the actual position and the display position over a prolonged interval, -to smooth the operation of the display and synchronize it with tape movement.
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, 3 ~i ~3 It is an objec-t of the present inventi.on -to lrnprove the apparatus and methods i:Llustra-ted in the above-:Ldentiied patent in such a manner that the dangers oE improper selection of cassette type are elim:inated by means of a reliable arrangemen-t which works automatically as soon as the tape is driven.
A further object of the.invention is to provide means for warning the user of the tape transport device of the necessity for a correction before the correction is carr:ied out.
Other objects and advantayes of the invention will bècome apparent upon reading the following detailed description and upon reference to the drawings in which:
Fi~ure 1 is a block diagram of a tape transport apparatus including a controller of the apparatus in accordance with the present invention;
Figure 2 is a block diagram similar to that of Figure 1, detailing the memory sections of the controller and diagrammatically illustrating the controller output to the display and motor control circuit for the reel drive motors of the tape transport apparatus;
Figure 3 is a timing diagram illustrating the.-timing of two reel revolutions by means of timing pulses for an elapsed period represented by sixteen reel pulses;
Figures 4 and 4A are a flow chart of the processor program in accordance with an embodiment of the invention;
Figure 5 is a simplified flow diagram of a subroutine executed by the CPU in response to an internal interrupt initiated csm/~
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~ hile the lnvention is suscept~ le to Var:i.oUY ~xliEicatlons ana alternative fo~ns, certain illus-tra-t:ive embodi~nts have been shor~n by way of example in the drawings and will here~n ke clescribed in detail. It should be understood, however, that it is not intended to limit the invention to the particular form disclosed, but, on the contrary, -the intention is to cover all nodifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims.
In particular it should be noted that the apparatus and methods disclosed relate generally to controlling the transfer of a flexible web member from a supply reel to a take up reel. Although not confined thereto, the invention relates more particu].arly to magnetic tape in a recording playback apparatus, more specifically of the cassette type.
In accomplishi.ng the objects of the present invention, the illustrated apparatus and method is characterized in that as the magnetic tape is travelling, such as for the normal play or record modes, signa].s are generated representing the velccities of both reels and values are calculated derived from these velocities. In the present case the calculated values involve at least two positions of the magnetic tapes which are compared with one another and the calculated values are generated from this comparison: the calculated values are further compared with an identifier or a reference value, and the t~pe of cassette which is indicated as having been selected is altered, or not altered, in accordance with the result of this latter comparison. In order to improve the accuracy and to prevent any errors in the correction of the type of cassette, the abovè described sequence is advantageously repeated several times before.
proceeding with a correction if this proves necessary. In order to warn the user of the tape device of -the necessity for a correction before it is carried out, provision is made for activati.ng a luminous signal, such as a flashing diode, after detection of the error in the selection of the type of cassette, in order to warn the user that the type of cassette selected ls csm/ ~
~ ,1 BS~3e8 not correct and that ~he la-t~er is belng au-tor~ ically correGt:ed.
In thc following descrlption, t~lO illustrative er~l3dim~n-ts will be described.
In accordance wi-th the rnethod and apparatus described in U.S.
Patent 4,172,231, if a cassette is introduced into the apparatus and a t~pe of tape cassette has been selec-ted, the microprocessor in the control unit for the tape device computes the position of the tape along its course of movement. The calculations are made when the supply and take up reels have both supplied a given number of pulses, and-a calculation result is transmitted to a diqital display and brought to -the attention of the user.
In a first embodiment of the invention, relating more particularly to the above-mentioned patent No. 4,172,231, -~nd with reference to Figures 4 an~ 4A herein, successive calculations of tape positions are made and utilized to determine if correction of a tape cassette type indication is necessary.
In carrying out the microprocessor program of this embodi~ent, a verifying coun-ter in the processor is utilized, and tape position calculations are obtained from the DETERMINE time or position element nun~ered 54 in the referenced patent. Similarly, cassette type indications are made through the cassette keys and internal and cassette constants are stored in processor memory. Further, a warning indica-ting diode must be added to the apparatus of the patent, under the control of the processor.
Referring now to the flow chæ t of Figures 4 and 4A, a sequence of operation for the microprocessor is illustrated. After the verifying counter, as shall be discussed in more detail hereinafter, has been reset to zero, the results of csm/ ~
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:
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each calculation of the tape position are stored. ~tsr that two calculations have been performed, the ~ost recent calculation of tape position is compared with that just previously obtained and the microprocessor determines the difference between these two results. This difference is then compared with the lnterval of time separating the two calculations, which may be measured advantageously with the aid of a clock contained in the mlcro-processor. If the difference between the tape positions does not fall within a reference interval "I" stored ln the micro-processor, a verifying counter, previously reset to zero, has its contents incremented by one unit. The use of an interval "I"
permits some deviation for a cassette from the statistical average without incrementing the verifying counter.
Once the value in the counter reaches three in a given interval T, which means, for example, that on three rechecks a difference has been measured which does not fall within the reference interval "I" stored, the microprocessor causes a diode to flash in order to alert the user to the fact that the selected type of cassette is incorrect.
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~ ~ 3 ~3'~)8 SLmultar1eous]y, ~he direction ~1nd ~ ni~ude o the Tneans of these dif~erences are de~errnined and the ~icroprocessor selects another type of cassette by compariny these with the reference values stored. The constants of this "assumed" type of cassette are then called up from the "cassette constants" mernory and used for the calculations of the tape position.
With the aid of these new constants the microprocessor continues to compare the difference between two successive calculations of the tape position with the interval separating these calculations. If the results of these comparisons remain within the reference interval "I" over three successive calculations it means that the new constants are in good agreernent with the cassette used and the indexing of the type of cassettes, done with the aid of light-emitting diodes is corrected correspondingly. Simultaneously, the exact position of the tape is indicated and the warning diode is swi-tched off.
If, on the other hand, the results of these comparisons do not fall within the reference interval "I" new constants corresponding to an "assumed" type of cassette are called up from the memory and the process continues until the correct constants corresponding to the t~pe of cassette used are selected.
In accordance with a second embodiment of the invention, a clock controlling the indicating device is used directly. Before describing the operation of the microprocessor in regard to this en~odiment, reference is made to Figures l and 2 which illustrate the associated control arrangement.
FIGS. l and 2 are block diagrams of tape transport apparatus h~lving a contral system constructed in accordance with the present invention and utilizing the methods of the present invention. The system, in general, includes a controller 36, a motor control circuit for the drive motors of the tape transport apparatus, a display for monitoring tape movement ~y visually ~'~ csm/~ 14 -.
1 J ~ 3 displaying tape position, an operatox panel with a key board and control switches, and reel speed detectors h~rein shown as pulse generators supplying information on reel speed to the controller 36. In the preferred form of the invention the controller 36 is comprised of a set of integrated circuit chips forming a micro-processor, an exemplary and preferred microprocessor being the Mostek F8 which includes a CPU unit 38 and one or more ~OM
memory units 40. As indicated in F~G. 2, the controller 36 includes a timer 42, which in the case of the Mostek F8 micro-processor is provided by the memory unit ~, and has an external reference frequency input 44 which provides a time base so that the timer is operable in real time.
While it is preferred to utilize a Mostek F8 family of chips to provide a microprocessor based controller 36, it will be appreciated that other microprocessors are available and may be used to serve the same functions, and that the controller may be implemented using other equivalent electronic devices.
When implemented with the Mostek F8 chips, the F8 CPU provides 64 bytes of RAM that may serve various register functions unique to the present invention, as well as provide read/write memory for arithmetic and logic functions. The CPU among other circuits also includes an arithmetic logic unit, an accumulator, I/O
ports, clock circuits, and interrupt logic which allows CPU
operation to be interrupted by a timer on the ROM chip or by an external source. One or more F8 ROM chips provide for storage of programs, I/O ports, a timer and program counter and stack register which handle the program function. With this construction, direct interfaces can be made by the controller 36 with peripheral devices since the CPU circuits provide~
for example, encoding and decoding circuits for operatin~ a display. The ROM's also provide ~or storage in coded signal form of the various unique constants required for ca3sette identification, search for target positions and other tape control functions peîformed by the apparatus, labeled ln FIG. 2 as memory sections or blocks Cassette I.~. Store~
Cassette Constants Store and Reel Pulse Count StorèO
Operator activated inputs to the controlle~ 36 are provided from an operator panel having one keyboard for diglt keys 0-3 and cassette keys 50 labeled C-45, C-60, C-90 and C-120, and a second keyboard with function keys 52 labeled play, record, stop, etc. which also includes the search mode key 54.
Apparatus activated inputs to the controller 36 lnclude detectors of speed of the reels of the cassettes or open web/reel assemblies in the tape transport apparatus, herein shown as including pulse generators 56, 58 on the spindles for reel 1, reel 2 respectively. Preferably the pulse generators 56, 58 are constructed to provide pulses at a rate representing reel angular velocity or rotational speed, and eight pulses per revolution of each reel is preferred for the rate, although the rate of pulse generation may, of course, be varied, and the speed detectors may, if desired, take other forms. Pulse streams or "reel pulses" from the pulse generators 56, 58 representing the rotational speed of the reels are supplied over input lines 60, 62 to the input/output ports 64 of the controller 36.
The tape transport apparatus includes drive motors Ml and M2 for the reels of the cassette or web/reel assembly which are controlled by a motor control circuit 66, which in turn is cntrolled by the controller 36.
The system provides for operation of the display 68 by the controller 36 over output lines 70 and 72 which, in the preferred form of the inventian, serve to drive the display to show in terms of time the position of the tape ln the tape transport apparatusO Illustratively the display will be in minutes and seconds, the display having 4 digits, a higher order and lower order di~it for the minutes and a higher order and a lower order diglt for the secondsO Associated wlth the ~16- ~
. ~ . . .
.
1 3 6~ 8 display are a set of lights 7~ ich are energizcd to indicate the functions being carried out by the apparatus under direction of the controller 36, such as play~ ~a3t ~orward, serach, e~c.
Another set of lights 76 is used to display the type o~ cassette in the apparatus~ those lights being labeled C~45, C-60, C-90, C-120 and WARNING. The function lights and cassette lights 74, 76 are driven from output lines 70 and through connections including the CPU circuits from the cassette keys 50 and function keys 52, so that manual activation of one of those keys also results in energizing the corresponding function or cassette light. ~he WARNING light is activated as shall ~e described hereinafter.
In somewhat more detail, the display 68 is operated by a display clock which is preferably served by a register of the CPU 38 of the controller 36, the display clock operating to update the display in synchronism with the movement of the tape as tape is moved from one reel to the other of a cassette or web/reel assembly.
The motor control circuit 66 is supplied with output signals from the input/output ports 64 of the controller and also with a variable supply voltage V between five to ten volts which is connected to the take-up reel drive motor Ml via operation of a relay in the motor control circuit 66.
The variable supply voltage is produced by the controller 36 in accordance with the tape position by placing a digital representation of the calculated supply voltage on a set of four output lines labeled Pl-O through Pl-3 which represent connections to input/output supports 64 of the controller 36. A circuit 80 schematically shown in FIG. l converts the representation of calculated supply voltage on combinations of the output lines Pl-0 through Pl-3 to the supply voltage for the take-up drive motor and thus serves as a type of digital to analog converter circuit to produce the d~slred , , , ~ 1 f;5~ ~ 8 vc~ric~ble nK~tor supply volt~ye.
PreEerably, in carrying out the various aspects oE the preserlt invention, programs for controlliny the processor 38 are stored in -the program n~mory section of the controller 36 as indicated in FIG. 2. It should ke recognized that while i-t is pref.erred to perform the methods and imp].ement the apparatus of this invention by a microprocessor under program control, the invention is not so limited and may be implemented by analogue circuits or discr.ete digital circuitry.
It is preferred to operate the CPU 38 of the controller 36 under program control to determine the absolute value of tape position in terms of time to the end of the tape on l-he takeoff reel. Such a position determination will be displayed by minutes and seconds on the display 68.
Tape position determination is made by calculations following position determination algorithms employing equation III' which, it will be recalled, re~ ires the ratio of rotational speeds of -the reels and numerical constants A ", B ", uniquely characterizing the physical parameters of the particular type of cassette or web/reel assembly loaded in the tape -transport apparatus.
In keeping with the present invention, numerical constants for the different known types of cassettes illustrativeIy C-45, C-60, C-90 and C-120 are stored in a "Cc~ssette Constants Store" provided by the memory unit 40 of the controller 36. Such numerical constants A ", B " are recalled from memory in the course of operation of the CPU under program control to c æ ry out the position dete.rmination algorithms. The ratio of rotational speeds of the reels is measured from th~ pulse streams received from -the pulse generators and representing the rotational speeds of the reels 1 and 2.
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Means for measuriny actual tirme is pro~/i.ded by -the timer 42 of -the con-troller 36. With the pulse yenerators 56, 58 providing eight pulses per revo]ution, 16 pu:Lses from either pulse generator represents -two comple-te revolutions of a reel. As shown in FIG. 3, 16 reel pulses are timed by accumulating high frequency pulses in a timing register which may be provided by one of the scratch pad registers of the CPU or by memory included in the controller 36. The high frequencv pulses accumulated in the timing reyister representing the elapsed time T2/Tl is calculated by division, such as by dividing the content of one timing register by the content of the other timing register to provide an equivalent reel speed ratio to the ratio P2/Pl derived by calculating the ratio of accumulated reel pulses as explained in the prior patent application.
Referring to equation III' as hereinbefore set forth, it will be seen that to make a calculation for t2 requires constant A'' and B'' plus the ratio of P2/Pl. To calculate t2 by the CPU under program control requires straightforward programming.
B csm/
:, i :1 6 ~ 3 The measured ratio of rotational speeds of the reels, based on the ratio of times T2 divided by Tl, it will be appreciated serves for the required ratio P2/Pl in the denominator of the fraction of equation III'.
While FIG. 3 illustrates timing the period of 16 reel pulses, the numbex may be varied as desired. For example, for determination of speed of the reels when tape is driven at fast speed, the CPU is preferably programmed to time 32 pulses from each reel, representing four revolutions of each reel. It will be recognized that the intermediate portion of tape for which a tape position determination is made, is that portion being transferred from reel to reel while the speed ratio is determined.
Referring to FIG. 5, this simplified flow diagram illustrates the program routine followed by the CPU in response to a timer interrupt request from the timer on the ROM~ The timer interrupt request may be initiated at any preselected time interval such as the time base clock frequency of 4 KHz or one-quarter millisecond. As shown in FIG. 5, the input lines from the pulse generators are tested and as pulses appear on one or the other of the input lines, registers for each reel which are initially set to a count of 16 are decremented until zeroed. Pulses at a rate determined by an internal master clock are clocked into and accumulated in a timing register for each reel, for the period of 16 pulses.
When the count reaches zero, afker 16 pulses have been received from the associated reel pulse generator, accumulated clock pulses for the 16 reel pulses are moved from the timing register .
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to another regis-ter and stored, -the conten-t o l-hat reglster then represen-ting the actual or real tim~ for 16 pulses. A speed ra-llo determination is made by dividing the content of one register wi.th the content of the other register, producing a speed ratio for use in the tape positlon determi.nation equation III".
In the system of the commonly assigned pri.or patent previously referred to, the controller updates the display of tape position based on periodic determinations of instantaneous positions of the tape. Considering the system constructed as preferred, in which tape position is displayed in terms of time to the end of the tape, if the tape position determination is repeated approximately every 6 - 8 seconds representing the rotation through two revolutions of both reels where both reels are half full of tape, if the display is updated to show the tape position after each cycle of determination the display will jump 6 - 8 seconds at a ti~le, and the jumps may be somewhat uneven.
As disclosed herein a method and means are provided for operating the display so that it is uniformly and smoothly updated to show changes in tape position of one second, the display being operated by a display clock in the intervals between tape position determinations, and the rate of the display clock being synchroni~ed with the actual rate of movement of the tape by comparing the actual tape positlon as determined each cycle, with the tape position shown on the display, and changing the rate of the display clock to eliminate any difference between the actual position and the display position over a prolonged interval, to smooth out the operation of the display.
An illustrative simplified program flow chart (FIG. 6) illustrates the programmed operation of the CPU 38 to drive csmh~"`
, I 1 6~36~3 the display 68 in this manner, it being unde~stood th~t a program will be stored in th~ program sectlon of ~he me~ory unit 40 to operate the CPU 38, as will be clea~ to a man skilled in this artO Turning firs~ to FIG. 1, to drive the display 68 combinations of output signals on the output line 70, 72 from I/o port 64 are connected to the circuitS of the display 50 which may be an LCD or ~D display unit of four digits to display minutes and seconds. The CPU 38 and memory 40 may provide the requisite decoder circuits to drive the display directly when Mostek F8 integrated circuits are used, or decoder circuits separate from the controller 36 may be provided where the controller is implemented in a dif~erent manner. Preferably, and in keeping with this invention, the CPU 38 under program control provides a display clock 78 which is connected to and controls the display 68.
Referring to FIG. 5, as there shown the main programmed operation of the CPU 38 is interrupted on a regular real time cycle by a timer interrupt request. The display clock 78 may be implemented by a register of the CPU 38 or RAM memory of the memory unit 40, which register is initially set to a value or content, and is decremented each cycle of the timer interrupt request, for example every 8ms. 9 50 that in the absence o~
adjustment the register times out each second and the display cIcck updates the display once each second. The nominal value loaded in the register is 125, 125 counts of 8 ms. giving one second decrementation. Due to time interrupts and other time consuming operations, the central value is 122 not 125. The time out of the display clock register, and thus the rate at which the display clock updates the display, is speeded up or slowed down, in accordance With the present invention, b~ loading the display clock register with ~ value ~reater or less than the central value by an amount which varies accord~ng to the sense and magnitude of the difference between the position ~hown on . . . . . ..... ..
... . _. _ , . .. . _ .
.
:
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the display clock and ~he actual position of the tape a~ deter-mined each cycle by the controllér. The value ~oaded in the register is read from memory as indicated in ~IGS. 7 and 7A, the displa~ clock being adjusted as the difference (~) between the display position "T" and the actual position "D" varieY
within a limit plus or minus 5 secondsO As indicated ln ~IG. 7, the display clock is sl~wed down if Q is greater than zero (with-in the 5 seconds), the calculation for the digital value to be added to the content of the register being based on smoothing constants that are indicated in FIGs. 7 and 7A. Thus if a is plus or minus less than 1 second, the constants value is 122, representing a median value for basing the calculation to adjust the time out of the display clock register. As indicated, the constants value increases and decreases incrementally as ~ is less than zero the value of the constants read from memory are from 122 to 91i as shown in FIG. 11 if ~ is greater than zero the constants read from memory are from 140 to 210.
Again referring to FIG. 6, in somewhat more detail, in response to operator initiation of the play function, the system enters the play mode of operation the function lights are set by the controllers 30, 36, and as indicated in the block "Set Smoothing Display Clock" an initial value is set into the register serving the function of the display clock.
The display clock register is therefore set to a content such that it will clock the display to update the display on a one second interval. As indicated in the next block in the flow chart, a 16 reel pulse count is set in registers for each reel;
This is to initialize ths circuits for timing the period of two revolutions of each ~eel. For this purpose, the stream of reel pulses issued from each reel pulse generator is counted until a total of 16 pulses, representing two revolutions of the ..
, ~ 1 B5f'~3 associated reel, has been receivedO
Turning back to FIGo 6, following the step of "Set 16 Reel }ulse Count in Registers for ~ach Reel" as there indi-cated the question i9 asked "Smoothing Clock Equals Zero?".
As also indicated in the timer interrupt flow chart of FIG.
5, the smoothing display clock is decremented each timer interrupt cycle, and if the smoothing display clock has been decremented to zero, as indicated in the flow chart in FIG.
6, the smoothing display clock is re~et and the display is decremented 1 second. If the smoothing clock does not equal zero, the routine ~umps from "Smoothing Clock Equals Zero?"
to the block "~as Reel Pulse Count Reached 16 Pulses from Each Reel?", representing that both registers for the reels have been decremented to zero and the time is ready to make position determination "D". If the display is blank, as it may be where this is the first position determination made by the controller, then the display is set to position "D";
if the display shows a position made by a prior determination, - 24 - .
, . . .
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the position shown in thc ~I;.splay llrll" and the l~osi~.ion "D"
just made are compared, and the value o~ "~ = T-~" is compu~efl.
If the dif:Eerence hetween the displayed position "T" and the just determined position "~" is within +5 seconds, then an adjustment is made of -the display clock rate. If the difference between the displayed and determined position is greater than 5 seconds, the display is updated to show the newly determined position "D". Thus, smoothing of the display operation by adjusting the rate of the display clock, is only carried out when the comparison between the displayed position and the newly determined position is within a 5 second interval.
Said smoothing is made over a prolonged interval which is on the order of 15 seconds, the digital. value to be added to the content of -the display clock register being calculated to change the rate of the display clock in a smooth manner so as to avoid any abrupt and noticeable increase or decrease in the normally one second changes in position shown on the display.
An electronic system is thus provided which allows control of the display in such a manner that the upda-ting of the tape position is done at every unit of time (each second) and the indicating rhythm is controlled by csm/') ~ :7 65~6~
a clock in such a manner that it can be speeded up or slowed down in accordance with the direction and the magnitude of any difference which occurs between the indicated position and the position calculated by the microprocessorO In this case, the direction and magnitude of the difference between this calculated position and the indicated position are stored at each calculation of the tape position as outlined in the flow chart of Figure 8.
The difference between the calculated position and the indicated position is then compared to a reference interval "I"' and, if the difference falls outside of this interval, a verifying counter, previously reset to zero, has its contents incremented by one unit. This verifying counter is advantageously selected from the counters and registers available in the micro-processor. From then on, the device operates in similar fashion to that described in regard to Figures 4 and 4A. Therefore the operation will not be further described in detail.
In a preferred implementation the interval T used for the verifying counter corresponds to the time which is required by the microprocessor for performing at least three successive calculations of the tape position. However, any other method of measuring the interval T can be used without deviating from the intent of the invention~ If a microprocessor is used in which, due to a lack of capacity, the reference tables, which ma~e is possible to "estimate" the type of cassette used by virtue of the result of comparisons with the reference interval cannot be stored, provision is made for the device described previously to try successively all of the different types of cassette. For example, successively C-60, C-90, C-120 ~if C-45 has been selected) will be tried until the results of the successive comparisons remain within the given reference intervalO Should this happen, for example, when using the v !- `
' .
1 1 6.5~-~B~
constants corresponding ~o khe type C~90, the indexing of the type of cassette is modified, the exact position of the magnetic tape is indicated and, simultaneously, the flashing diode i~
disabled.
An al~ernative cassette type indication correction method is illustrated in the flow chart of Figure 9. As shown therein the microprocessor utilizes the clock driving the display in accordance with the flow chart. The timer corresponds to the "~ = T - D" as computed in the flow chart of Figure 6. When the tape is being driven at PLAY speed, the rate of the smoothing clock is permanently checked. Each time the display is fast or slow by an amount of three seconds, the number 2 is respectively added to or subtracted from the contents of a special xegieter, internal to the processor, initially reset to zero at the beginning of PLAY. When the contents of this special register exceed ~3 or -4, the warning LED is switched on. Also, a flag is set and
` ` Description o~ the Inven~ion _ _ __ . ___ rL~Ie presenl: invent:ion relates to improvel~nts in m~thc~s and apparatus for inclica-ting the rx,sition of a fleYibl~ w~b being transferred from one ree] to a second reel in a ~eb/reel assen~ly, and more particularly concerns tape transport apparatus for tape casse-ttes and the determination of whether or not the type of cassette selected or inclicated is correct so that valid position information may be provided for the tape.
In U.S. Patent No. 4,172,231, commonly assigned with the present application, a me-thod and apparatus is illustrated which provides precise indications of the position of a tape during its transfer from a supply reel to a take up reel.
According to the teachings of the above mentioned patent, the rotational speeds of a supply reel and a take up reel are measured, and the ratio between these measurements is established independently of the speed and the direction of movement of the tape. Reference data in the form of constants representing the characteristics of different types of reels and tapes, such as specific cassette type identifications, are stored in the device, and the reference data or constants corresponding to the reels and tape in use are manually selected and are utilized in calculations. Intermediate signals representing the ratio between the rotational speeds of the supply reel and the take up reel are generated, and with the aid o these intermediate signals and of the reference data or constants, output slgnals are produced as a function of the instantaneous position of the tape with respect to one and/or the other of one of its ends. The output signals are used for indicating the position of the tape and/or for controlling certain operations of the tape device.
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~ he manua] se:Lec-tLon of cons~ants correspondincJ
to the t~pe of casset-te uged lnvolves ~he clan~er of a u~er selectiny the wrong cassette -type. Irhis rnay lea~l to ~aul-t~
indication of tape position, and a-t hiyh speeds prema-ture slowing down wi-th unnecessary increase in winding and unwinding times, or even no slowiny do~n at the end of the tape with consequent danger of tape breakage and so on.
The invention of the aforesaid U.S. Patent No. 4,172, 231 is described therein as useful in transport apparatus for reel/web assemblies the physical parameters of which are known, the physical parameters including the tape length and thickness, and the reel hub diameters. In such a transport apparatus operating with a web/reel assembly having known physical parameters, the position relative to one end of the web of an intermediate portion being transferred from one reel to the other, may be determined by a computational process using mathematical equations, i.e. by following tape position determination algorithms employing constants established by the known physical parameters of that reel/web assembly, and a ~ariable parameter; namely, the ratio of rotational speeds of the two reels at the intermediate web portion is being transferred from one reel to the other, which ratio continuously csm/~
.
~ 3 ~ f; ~3 changes as the web is transfer~ed. It is explained in saia prior patent that the same algorithms employing the same constants may be followed to determine the position o~ an intermediate web portion at any stage of transfer of the web the only input required at any ~tage is the ratio of the rotational speeds of the reels. By determining tape position in a regularly repea~ing cycle, using said tape positio~
determination algorithms, and producing each cycle an output signal representing the position determined for the web during that cycle, the output signals may be utilized to monitor the transfer of the web in the apparatus, for example, by displaying the continuously changing position of the web or controlling the operation of the transport apparatus.
The method of said prior patent is particularly, although not exclusively, useful in tape transport apparatus for cassettes of tape which are a standard type for example, cassettes providing sixty, ninety and one hundred twenty minutes of playing time known, respectively, as C-60, C-90 and C-120 cassettes. Such cassettes are conventional with two reels and different known lengths and thickness of tape to provide the various lengths of playing time. The method entails first establishing constants for each tape cassette, which constants are used in the position determination algorithms, and storing a set of constants for each tape cassette in, for example, a semiconductor memory unit. In tape transport apparatus under the control of a microprocessor, signals representing the set of constants corresponding to the cassette loaded into the transport apparatus, are recalled from the memory uni~, intermediate signals are generated representing the ratio Pl/P2 measuring the rotational speeds of the reels, and by circuit means such as the microprocessor under program con~rol a determination is made of tape position in terms of the length ~1 or Q 2) or time ttl or t2) to the end of the web on eithar reel of an intermediate portion of the web being .
i .1 ~ 6 ~
transferred from one reel to the other, using positiondetermination algorithms employing the following equations:
Equation (I) Ql A B
1 ~ (P2) (take-up reel) -Equation (I)' Q 2 A
( 2)2 (supply reel) wherein A - L ' T + 1 and B = L
T 1 T2 _ 1 , L representing the total length of magnetic tape, Ql representing the used tape,~ 2~ the remaining tape, T representing the ratio Pl/P2 when L = ~2 i.e. at the beginning of the tape. T is thus a constant which characterizes each type of cassette and which can be determined either mathematically or ~y experiment.
If the two terms of the Equation (I) and (I)' are divided by L, we obtain the following:
With A = A' = T + 1 and B = B' =
L T2 _ 1 L T2 _ 1 E~uation (II) Rl = Al - B! and 1 +~ _\2 ~,P2 1 Equation (II)' R2 = A~ B' L 1 +~ ~ 2 ~ 11 It is also possible to multiply the two terms o~ quation -~: : ' ' ' '', '. ' ' ' ' ; ' ' ' ' ' ':
~.
: ' ~ 165~36~3 II and II' by the duration Z of the cassette, of which the usual types may have the values defined aboveO We then obtain, with-A" = A' x ~ and B " = B' x the followingo Equation (III) tl = A " - B'' 1 + ~P
~P2l Equation (III)' t2 = " ~ B "
Pl Among the other Equations, (I~ and (K)' represent the length of the magnetic tape wound on the take-up reel and on the supply reel respectively, i.e. a position determination in terms of linear dimension. Equations (II) and (II)' represent the ratios of the length of the magnetic tape wound on the take-up reel and on the supply reel respectively to its total length, i.e. a position indication in non-dimensional terms, while Equations (III) and (III)' represent the time taken by th`e magnetic tape to reach the radius Rl on the taXe~up reel and the radius R2 on the supply reel respectively, i.e. a position indication in terms of time, representing the playback time or recording time which has elapsed since the beginning of the magnetic tape or which remains until the end of the magnetic tape respectively~
The sets of constants, A, A'~ ~'', and B, B', B'' for tbe different types of cassettes are determined statistically, so that account can be taken, with sufficient accuracy, of the very slight variations which may exist between different ca~
settes of one and the same type and which result, for example, ..
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from production toler~nces. Cons~arlts ~or the C'~]~0 tar~ casselte have been measured as ~" - 72.2496 and s'' -- 5.996l, as an ex~r~ple of constan-ts for use in web position determination using E~uation III'.
- ~ccording to the rrethod disclosed in said prior patent No.
4,172,231, the rotational speeds of the reels are represented by pulse streams from pulse yenerators driven responsive to rotation of each reel. Pulses at the rate of twenty per revolu-tion of each reel are fed to shift reyisters which accumulate the pulses and reel speed ratios are calculated based on the total number of pulses accumulated in the registers. It was recognized that the accumulated total of pulses in a shift register provided only an approximate representation of the instantaneous rotational speed of one of the reels.
As an improved method over that disclosed in Patent 4,172,231 instantaneous reel speed ratios are calculated based on the real time for each reel to make two revolutions when driven at normal (play or record) speed, and four revolutions when driven at fast (forward or rewind) speed.
For this improved method, pulse genera-tors on the reel spindles produce eight pulses (hereinafter called "reel pulses") each revolution of the reel, which pulses are counted. Clock pulses generated at a rate determined by an internal clock, illustratively 4 KHz, are clocked into and accumulated in a timing reyister for each reel for the time period elapsed until either i6 or 32 reel pulses are counted, the content oE each of the timiny registers then representiny the real time for two or four revolutions of each of the reels; instantaneous reel speed ratios are calculated by dividing the conten-ts of the timing registers.
Further, according to this improved method, an unknown web/reel assembly or cassette is identified by first recalliny from memory predetermined values of constants, which are called I.D. constants, and then proceeding through a '''"'` /?
, '. . ' :.'. ~ . ' ~ ~ B~8 cassette identifying process in which a first tape positio~
determination is made based on the recalled numerical constants, the tape is moved a prescribed distance, a second tape position determination i5 made, the actual prescribed distance is compared with the theoretical distance between the first and second determined positions and in accordance with that comparison, the unknown cassette is determined to be one of the known types, and thus the unknown cassette is identified.
In carrying out the I.D. mode of operation preferably the two positions are determined by operation of a microprocessor under program control using position determination algorithms including one of the equations (I) to (III)' referred to above for computing tape positions employing numerical constants derived from the I.D. constants store, and reel speed ratio i5 measured as the tape is transferred from reel to reel. The two predetermined positions can be selected in arbitrary mannex, and may in particular be fixed by predetermined numbers of revolutions of the reels or pul3es supplied by the rotàtional speed detector or detectors (pulse generators) of one and/or the other of the reels. The process is thus based on measuring the rotational velocity of each of the reels, which velocity is dependent on their characteristics, their state of winding, and the type of tape used.
This method for automatically identifying an unknown cassette as one of a plurality of known types, is implemented in tape transport apparatus operated under the control of a controller that includes a central processor unit (CPU) and associated memory units (ROM) for programs and storage of numerical constants representing the cassettesl and the cassette I~Do constants.
Tape transport apparatus including reel drive motors and motor control circuits thereforl is controlled by the microprocessor type controller to perform the IoDo mode of operation in which .
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the tape is movecl frorn a starti.ng posi-ti.on at no-rr~al sr~ed for -the f;:rcit tape position deterrnination, at fast speed to the .æcond pos:iti.on, at normal speed for -the second tape posi-tion de-termination, and after the cassette is identified, the tape is returned to thc starting position.
m e microprocessor under program control provides means for deterrnining the first and second tape positions, means for calculating the theoretical difference be-tween the first and second posi-tions, means for rneasuring the actual difference between the same positions, means for cornparing -the theoretical and actual differences and in accordance with the comparison confirming tha-t the unknown cassette is of one or of another known t~pe.
In the system descri.bed in the above-rnentioned patent, a display is operated by the controller to display successive tape positions determined by the controller following several revolutions of both ree].s. If such display is updated to show the tape position each such deterrnination, the display may jump 6 to 8 seconds at a time and the jumps may be uneven. In contrast, by the improved method, provi.sion is made for operating such a display so that the display is uniformly and smoothly updated to show changes in tape position. For example, where tape position is displayed -in terms oE t.ime to the end of the tape, the display is operated to show changes in taFe position of one second, the display being operated by a display clock and the rate of the display clock being synchronized wi-th the actual rate of movement of the -tape by comparing-the actual tape position as determined each cycle with the tape position shown on the display, and changing the rate of the display clock to eliminate any diE:Eerence between the actual position and the display position over a prolonged interval, -to smooth the operation of the display and synchronize it with tape movement.
csm/~
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, 3 ~i ~3 It is an objec-t of the present inventi.on -to lrnprove the apparatus and methods i:Llustra-ted in the above-:Ldentiied patent in such a manner that the dangers oE improper selection of cassette type are elim:inated by means of a reliable arrangemen-t which works automatically as soon as the tape is driven.
A further object of the.invention is to provide means for warning the user of the tape transport device of the necessity for a correction before the correction is carr:ied out.
Other objects and advantayes of the invention will bècome apparent upon reading the following detailed description and upon reference to the drawings in which:
Fi~ure 1 is a block diagram of a tape transport apparatus including a controller of the apparatus in accordance with the present invention;
Figure 2 is a block diagram similar to that of Figure 1, detailing the memory sections of the controller and diagrammatically illustrating the controller output to the display and motor control circuit for the reel drive motors of the tape transport apparatus;
Figure 3 is a timing diagram illustrating the.-timing of two reel revolutions by means of timing pulses for an elapsed period represented by sixteen reel pulses;
Figures 4 and 4A are a flow chart of the processor program in accordance with an embodiment of the invention;
Figure 5 is a simplified flow diagram of a subroutine executed by the CPU in response to an internal interrupt initiated csm/~
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~ hile the lnvention is suscept~ le to Var:i.oUY ~xliEicatlons ana alternative fo~ns, certain illus-tra-t:ive embodi~nts have been shor~n by way of example in the drawings and will here~n ke clescribed in detail. It should be understood, however, that it is not intended to limit the invention to the particular form disclosed, but, on the contrary, -the intention is to cover all nodifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims.
In particular it should be noted that the apparatus and methods disclosed relate generally to controlling the transfer of a flexible web member from a supply reel to a take up reel. Although not confined thereto, the invention relates more particu].arly to magnetic tape in a recording playback apparatus, more specifically of the cassette type.
In accomplishi.ng the objects of the present invention, the illustrated apparatus and method is characterized in that as the magnetic tape is travelling, such as for the normal play or record modes, signa].s are generated representing the velccities of both reels and values are calculated derived from these velocities. In the present case the calculated values involve at least two positions of the magnetic tapes which are compared with one another and the calculated values are generated from this comparison: the calculated values are further compared with an identifier or a reference value, and the t~pe of cassette which is indicated as having been selected is altered, or not altered, in accordance with the result of this latter comparison. In order to improve the accuracy and to prevent any errors in the correction of the type of cassette, the abovè described sequence is advantageously repeated several times before.
proceeding with a correction if this proves necessary. In order to warn the user of the tape device of -the necessity for a correction before it is carried out, provision is made for activati.ng a luminous signal, such as a flashing diode, after detection of the error in the selection of the type of cassette, in order to warn the user that the type of cassette selected ls csm/ ~
~ ,1 BS~3e8 not correct and that ~he la-t~er is belng au-tor~ ically correGt:ed.
In thc following descrlption, t~lO illustrative er~l3dim~n-ts will be described.
In accordance wi-th the rnethod and apparatus described in U.S.
Patent 4,172,231, if a cassette is introduced into the apparatus and a t~pe of tape cassette has been selec-ted, the microprocessor in the control unit for the tape device computes the position of the tape along its course of movement. The calculations are made when the supply and take up reels have both supplied a given number of pulses, and-a calculation result is transmitted to a diqital display and brought to -the attention of the user.
In a first embodiment of the invention, relating more particularly to the above-mentioned patent No. 4,172,231, -~nd with reference to Figures 4 an~ 4A herein, successive calculations of tape positions are made and utilized to determine if correction of a tape cassette type indication is necessary.
In carrying out the microprocessor program of this embodi~ent, a verifying coun-ter in the processor is utilized, and tape position calculations are obtained from the DETERMINE time or position element nun~ered 54 in the referenced patent. Similarly, cassette type indications are made through the cassette keys and internal and cassette constants are stored in processor memory. Further, a warning indica-ting diode must be added to the apparatus of the patent, under the control of the processor.
Referring now to the flow chæ t of Figures 4 and 4A, a sequence of operation for the microprocessor is illustrated. After the verifying counter, as shall be discussed in more detail hereinafter, has been reset to zero, the results of csm/ ~
B
:
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each calculation of the tape position are stored. ~tsr that two calculations have been performed, the ~ost recent calculation of tape position is compared with that just previously obtained and the microprocessor determines the difference between these two results. This difference is then compared with the lnterval of time separating the two calculations, which may be measured advantageously with the aid of a clock contained in the mlcro-processor. If the difference between the tape positions does not fall within a reference interval "I" stored ln the micro-processor, a verifying counter, previously reset to zero, has its contents incremented by one unit. The use of an interval "I"
permits some deviation for a cassette from the statistical average without incrementing the verifying counter.
Once the value in the counter reaches three in a given interval T, which means, for example, that on three rechecks a difference has been measured which does not fall within the reference interval "I" stored, the microprocessor causes a diode to flash in order to alert the user to the fact that the selected type of cassette is incorrect.
-~
.
~ ~ 3 ~3'~)8 SLmultar1eous]y, ~he direction ~1nd ~ ni~ude o the Tneans of these dif~erences are de~errnined and the ~icroprocessor selects another type of cassette by compariny these with the reference values stored. The constants of this "assumed" type of cassette are then called up from the "cassette constants" mernory and used for the calculations of the tape position.
With the aid of these new constants the microprocessor continues to compare the difference between two successive calculations of the tape position with the interval separating these calculations. If the results of these comparisons remain within the reference interval "I" over three successive calculations it means that the new constants are in good agreernent with the cassette used and the indexing of the type of cassettes, done with the aid of light-emitting diodes is corrected correspondingly. Simultaneously, the exact position of the tape is indicated and the warning diode is swi-tched off.
If, on the other hand, the results of these comparisons do not fall within the reference interval "I" new constants corresponding to an "assumed" type of cassette are called up from the memory and the process continues until the correct constants corresponding to the t~pe of cassette used are selected.
In accordance with a second embodiment of the invention, a clock controlling the indicating device is used directly. Before describing the operation of the microprocessor in regard to this en~odiment, reference is made to Figures l and 2 which illustrate the associated control arrangement.
FIGS. l and 2 are block diagrams of tape transport apparatus h~lving a contral system constructed in accordance with the present invention and utilizing the methods of the present invention. The system, in general, includes a controller 36, a motor control circuit for the drive motors of the tape transport apparatus, a display for monitoring tape movement ~y visually ~'~ csm/~ 14 -.
1 J ~ 3 displaying tape position, an operatox panel with a key board and control switches, and reel speed detectors h~rein shown as pulse generators supplying information on reel speed to the controller 36. In the preferred form of the invention the controller 36 is comprised of a set of integrated circuit chips forming a micro-processor, an exemplary and preferred microprocessor being the Mostek F8 which includes a CPU unit 38 and one or more ~OM
memory units 40. As indicated in F~G. 2, the controller 36 includes a timer 42, which in the case of the Mostek F8 micro-processor is provided by the memory unit ~, and has an external reference frequency input 44 which provides a time base so that the timer is operable in real time.
While it is preferred to utilize a Mostek F8 family of chips to provide a microprocessor based controller 36, it will be appreciated that other microprocessors are available and may be used to serve the same functions, and that the controller may be implemented using other equivalent electronic devices.
When implemented with the Mostek F8 chips, the F8 CPU provides 64 bytes of RAM that may serve various register functions unique to the present invention, as well as provide read/write memory for arithmetic and logic functions. The CPU among other circuits also includes an arithmetic logic unit, an accumulator, I/O
ports, clock circuits, and interrupt logic which allows CPU
operation to be interrupted by a timer on the ROM chip or by an external source. One or more F8 ROM chips provide for storage of programs, I/O ports, a timer and program counter and stack register which handle the program function. With this construction, direct interfaces can be made by the controller 36 with peripheral devices since the CPU circuits provide~
for example, encoding and decoding circuits for operatin~ a display. The ROM's also provide ~or storage in coded signal form of the various unique constants required for ca3sette identification, search for target positions and other tape control functions peîformed by the apparatus, labeled ln FIG. 2 as memory sections or blocks Cassette I.~. Store~
Cassette Constants Store and Reel Pulse Count StorèO
Operator activated inputs to the controlle~ 36 are provided from an operator panel having one keyboard for diglt keys 0-3 and cassette keys 50 labeled C-45, C-60, C-90 and C-120, and a second keyboard with function keys 52 labeled play, record, stop, etc. which also includes the search mode key 54.
Apparatus activated inputs to the controller 36 lnclude detectors of speed of the reels of the cassettes or open web/reel assemblies in the tape transport apparatus, herein shown as including pulse generators 56, 58 on the spindles for reel 1, reel 2 respectively. Preferably the pulse generators 56, 58 are constructed to provide pulses at a rate representing reel angular velocity or rotational speed, and eight pulses per revolution of each reel is preferred for the rate, although the rate of pulse generation may, of course, be varied, and the speed detectors may, if desired, take other forms. Pulse streams or "reel pulses" from the pulse generators 56, 58 representing the rotational speed of the reels are supplied over input lines 60, 62 to the input/output ports 64 of the controller 36.
The tape transport apparatus includes drive motors Ml and M2 for the reels of the cassette or web/reel assembly which are controlled by a motor control circuit 66, which in turn is cntrolled by the controller 36.
The system provides for operation of the display 68 by the controller 36 over output lines 70 and 72 which, in the preferred form of the inventian, serve to drive the display to show in terms of time the position of the tape ln the tape transport apparatusO Illustratively the display will be in minutes and seconds, the display having 4 digits, a higher order and lower order di~it for the minutes and a higher order and a lower order diglt for the secondsO Associated wlth the ~16- ~
. ~ . . .
.
1 3 6~ 8 display are a set of lights 7~ ich are energizcd to indicate the functions being carried out by the apparatus under direction of the controller 36, such as play~ ~a3t ~orward, serach, e~c.
Another set of lights 76 is used to display the type o~ cassette in the apparatus~ those lights being labeled C~45, C-60, C-90, C-120 and WARNING. The function lights and cassette lights 74, 76 are driven from output lines 70 and through connections including the CPU circuits from the cassette keys 50 and function keys 52, so that manual activation of one of those keys also results in energizing the corresponding function or cassette light. ~he WARNING light is activated as shall ~e described hereinafter.
In somewhat more detail, the display 68 is operated by a display clock which is preferably served by a register of the CPU 38 of the controller 36, the display clock operating to update the display in synchronism with the movement of the tape as tape is moved from one reel to the other of a cassette or web/reel assembly.
The motor control circuit 66 is supplied with output signals from the input/output ports 64 of the controller and also with a variable supply voltage V between five to ten volts which is connected to the take-up reel drive motor Ml via operation of a relay in the motor control circuit 66.
The variable supply voltage is produced by the controller 36 in accordance with the tape position by placing a digital representation of the calculated supply voltage on a set of four output lines labeled Pl-O through Pl-3 which represent connections to input/output supports 64 of the controller 36. A circuit 80 schematically shown in FIG. l converts the representation of calculated supply voltage on combinations of the output lines Pl-0 through Pl-3 to the supply voltage for the take-up drive motor and thus serves as a type of digital to analog converter circuit to produce the d~slred , , , ~ 1 f;5~ ~ 8 vc~ric~ble nK~tor supply volt~ye.
PreEerably, in carrying out the various aspects oE the preserlt invention, programs for controlliny the processor 38 are stored in -the program n~mory section of the controller 36 as indicated in FIG. 2. It should ke recognized that while i-t is pref.erred to perform the methods and imp].ement the apparatus of this invention by a microprocessor under program control, the invention is not so limited and may be implemented by analogue circuits or discr.ete digital circuitry.
It is preferred to operate the CPU 38 of the controller 36 under program control to determine the absolute value of tape position in terms of time to the end of the tape on l-he takeoff reel. Such a position determination will be displayed by minutes and seconds on the display 68.
Tape position determination is made by calculations following position determination algorithms employing equation III' which, it will be recalled, re~ ires the ratio of rotational speeds of -the reels and numerical constants A ", B ", uniquely characterizing the physical parameters of the particular type of cassette or web/reel assembly loaded in the tape -transport apparatus.
In keeping with the present invention, numerical constants for the different known types of cassettes illustrativeIy C-45, C-60, C-90 and C-120 are stored in a "Cc~ssette Constants Store" provided by the memory unit 40 of the controller 36. Such numerical constants A ", B " are recalled from memory in the course of operation of the CPU under program control to c æ ry out the position dete.rmination algorithms. The ratio of rotational speeds of the reels is measured from th~ pulse streams received from -the pulse generators and representing the rotational speeds of the reels 1 and 2.
csm/S'-~ . .
~ , ' ~ :i 6i~:~fj~
Means for measuriny actual tirme is pro~/i.ded by -the timer 42 of -the con-troller 36. With the pulse yenerators 56, 58 providing eight pulses per revo]ution, 16 pu:Lses from either pulse generator represents -two comple-te revolutions of a reel. As shown in FIG. 3, 16 reel pulses are timed by accumulating high frequency pulses in a timing register which may be provided by one of the scratch pad registers of the CPU or by memory included in the controller 36. The high frequencv pulses accumulated in the timing reyister representing the elapsed time T2/Tl is calculated by division, such as by dividing the content of one timing register by the content of the other timing register to provide an equivalent reel speed ratio to the ratio P2/Pl derived by calculating the ratio of accumulated reel pulses as explained in the prior patent application.
Referring to equation III' as hereinbefore set forth, it will be seen that to make a calculation for t2 requires constant A'' and B'' plus the ratio of P2/Pl. To calculate t2 by the CPU under program control requires straightforward programming.
B csm/
:, i :1 6 ~ 3 The measured ratio of rotational speeds of the reels, based on the ratio of times T2 divided by Tl, it will be appreciated serves for the required ratio P2/Pl in the denominator of the fraction of equation III'.
While FIG. 3 illustrates timing the period of 16 reel pulses, the numbex may be varied as desired. For example, for determination of speed of the reels when tape is driven at fast speed, the CPU is preferably programmed to time 32 pulses from each reel, representing four revolutions of each reel. It will be recognized that the intermediate portion of tape for which a tape position determination is made, is that portion being transferred from reel to reel while the speed ratio is determined.
Referring to FIG. 5, this simplified flow diagram illustrates the program routine followed by the CPU in response to a timer interrupt request from the timer on the ROM~ The timer interrupt request may be initiated at any preselected time interval such as the time base clock frequency of 4 KHz or one-quarter millisecond. As shown in FIG. 5, the input lines from the pulse generators are tested and as pulses appear on one or the other of the input lines, registers for each reel which are initially set to a count of 16 are decremented until zeroed. Pulses at a rate determined by an internal master clock are clocked into and accumulated in a timing register for each reel, for the period of 16 pulses.
When the count reaches zero, afker 16 pulses have been received from the associated reel pulse generator, accumulated clock pulses for the 16 reel pulses are moved from the timing register .
" , -- -- , .
S:3 ~ ~
to another regis-ter and stored, -the conten-t o l-hat reglster then represen-ting the actual or real tim~ for 16 pulses. A speed ra-llo determination is made by dividing the content of one register wi.th the content of the other register, producing a speed ratio for use in the tape positlon determi.nation equation III".
In the system of the commonly assigned pri.or patent previously referred to, the controller updates the display of tape position based on periodic determinations of instantaneous positions of the tape. Considering the system constructed as preferred, in which tape position is displayed in terms of time to the end of the tape, if the tape position determination is repeated approximately every 6 - 8 seconds representing the rotation through two revolutions of both reels where both reels are half full of tape, if the display is updated to show the tape position after each cycle of determination the display will jump 6 - 8 seconds at a ti~le, and the jumps may be somewhat uneven.
As disclosed herein a method and means are provided for operating the display so that it is uniformly and smoothly updated to show changes in tape position of one second, the display being operated by a display clock in the intervals between tape position determinations, and the rate of the display clock being synchroni~ed with the actual rate of movement of the tape by comparing the actual tape positlon as determined each cycle, with the tape position shown on the display, and changing the rate of the display clock to eliminate any difference between the actual position and the display position over a prolonged interval, to smooth out the operation of the display.
An illustrative simplified program flow chart (FIG. 6) illustrates the programmed operation of the CPU 38 to drive csmh~"`
, I 1 6~36~3 the display 68 in this manner, it being unde~stood th~t a program will be stored in th~ program sectlon of ~he me~ory unit 40 to operate the CPU 38, as will be clea~ to a man skilled in this artO Turning firs~ to FIG. 1, to drive the display 68 combinations of output signals on the output line 70, 72 from I/o port 64 are connected to the circuitS of the display 50 which may be an LCD or ~D display unit of four digits to display minutes and seconds. The CPU 38 and memory 40 may provide the requisite decoder circuits to drive the display directly when Mostek F8 integrated circuits are used, or decoder circuits separate from the controller 36 may be provided where the controller is implemented in a dif~erent manner. Preferably, and in keeping with this invention, the CPU 38 under program control provides a display clock 78 which is connected to and controls the display 68.
Referring to FIG. 5, as there shown the main programmed operation of the CPU 38 is interrupted on a regular real time cycle by a timer interrupt request. The display clock 78 may be implemented by a register of the CPU 38 or RAM memory of the memory unit 40, which register is initially set to a value or content, and is decremented each cycle of the timer interrupt request, for example every 8ms. 9 50 that in the absence o~
adjustment the register times out each second and the display cIcck updates the display once each second. The nominal value loaded in the register is 125, 125 counts of 8 ms. giving one second decrementation. Due to time interrupts and other time consuming operations, the central value is 122 not 125. The time out of the display clock register, and thus the rate at which the display clock updates the display, is speeded up or slowed down, in accordance With the present invention, b~ loading the display clock register with ~ value ~reater or less than the central value by an amount which varies accord~ng to the sense and magnitude of the difference between the position ~hown on . . . . . ..... ..
... . _. _ , . .. . _ .
.
:
, .
~ 1 6.~
the display clock and ~he actual position of the tape a~ deter-mined each cycle by the controllér. The value ~oaded in the register is read from memory as indicated in ~IGS. 7 and 7A, the displa~ clock being adjusted as the difference (~) between the display position "T" and the actual position "D" varieY
within a limit plus or minus 5 secondsO As indicated ln ~IG. 7, the display clock is sl~wed down if Q is greater than zero (with-in the 5 seconds), the calculation for the digital value to be added to the content of the register being based on smoothing constants that are indicated in FIGs. 7 and 7A. Thus if a is plus or minus less than 1 second, the constants value is 122, representing a median value for basing the calculation to adjust the time out of the display clock register. As indicated, the constants value increases and decreases incrementally as ~ is less than zero the value of the constants read from memory are from 122 to 91i as shown in FIG. 11 if ~ is greater than zero the constants read from memory are from 140 to 210.
Again referring to FIG. 6, in somewhat more detail, in response to operator initiation of the play function, the system enters the play mode of operation the function lights are set by the controllers 30, 36, and as indicated in the block "Set Smoothing Display Clock" an initial value is set into the register serving the function of the display clock.
The display clock register is therefore set to a content such that it will clock the display to update the display on a one second interval. As indicated in the next block in the flow chart, a 16 reel pulse count is set in registers for each reel;
This is to initialize ths circuits for timing the period of two revolutions of each ~eel. For this purpose, the stream of reel pulses issued from each reel pulse generator is counted until a total of 16 pulses, representing two revolutions of the ..
, ~ 1 B5f'~3 associated reel, has been receivedO
Turning back to FIGo 6, following the step of "Set 16 Reel }ulse Count in Registers for ~ach Reel" as there indi-cated the question i9 asked "Smoothing Clock Equals Zero?".
As also indicated in the timer interrupt flow chart of FIG.
5, the smoothing display clock is decremented each timer interrupt cycle, and if the smoothing display clock has been decremented to zero, as indicated in the flow chart in FIG.
6, the smoothing display clock is re~et and the display is decremented 1 second. If the smoothing clock does not equal zero, the routine ~umps from "Smoothing Clock Equals Zero?"
to the block "~as Reel Pulse Count Reached 16 Pulses from Each Reel?", representing that both registers for the reels have been decremented to zero and the time is ready to make position determination "D". If the display is blank, as it may be where this is the first position determination made by the controller, then the display is set to position "D";
if the display shows a position made by a prior determination, - 24 - .
, . . .
~: ' ~ 1 ~55~
the position shown in thc ~I;.splay llrll" and the l~osi~.ion "D"
just made are compared, and the value o~ "~ = T-~" is compu~efl.
If the dif:Eerence hetween the displayed position "T" and the just determined position "~" is within +5 seconds, then an adjustment is made of -the display clock rate. If the difference between the displayed and determined position is greater than 5 seconds, the display is updated to show the newly determined position "D". Thus, smoothing of the display operation by adjusting the rate of the display clock, is only carried out when the comparison between the displayed position and the newly determined position is within a 5 second interval.
Said smoothing is made over a prolonged interval which is on the order of 15 seconds, the digital. value to be added to the content of -the display clock register being calculated to change the rate of the display clock in a smooth manner so as to avoid any abrupt and noticeable increase or decrease in the normally one second changes in position shown on the display.
An electronic system is thus provided which allows control of the display in such a manner that the upda-ting of the tape position is done at every unit of time (each second) and the indicating rhythm is controlled by csm/') ~ :7 65~6~
a clock in such a manner that it can be speeded up or slowed down in accordance with the direction and the magnitude of any difference which occurs between the indicated position and the position calculated by the microprocessorO In this case, the direction and magnitude of the difference between this calculated position and the indicated position are stored at each calculation of the tape position as outlined in the flow chart of Figure 8.
The difference between the calculated position and the indicated position is then compared to a reference interval "I"' and, if the difference falls outside of this interval, a verifying counter, previously reset to zero, has its contents incremented by one unit. This verifying counter is advantageously selected from the counters and registers available in the micro-processor. From then on, the device operates in similar fashion to that described in regard to Figures 4 and 4A. Therefore the operation will not be further described in detail.
In a preferred implementation the interval T used for the verifying counter corresponds to the time which is required by the microprocessor for performing at least three successive calculations of the tape position. However, any other method of measuring the interval T can be used without deviating from the intent of the invention~ If a microprocessor is used in which, due to a lack of capacity, the reference tables, which ma~e is possible to "estimate" the type of cassette used by virtue of the result of comparisons with the reference interval cannot be stored, provision is made for the device described previously to try successively all of the different types of cassette. For example, successively C-60, C-90, C-120 ~if C-45 has been selected) will be tried until the results of the successive comparisons remain within the given reference intervalO Should this happen, for example, when using the v !- `
' .
1 1 6.5~-~B~
constants corresponding ~o khe type C~90, the indexing of the type of cassette is modified, the exact position of the magnetic tape is indicated and, simultaneously, the flashing diode i~
disabled.
An al~ernative cassette type indication correction method is illustrated in the flow chart of Figure 9. As shown therein the microprocessor utilizes the clock driving the display in accordance with the flow chart. The timer corresponds to the "~ = T - D" as computed in the flow chart of Figure 6. When the tape is being driven at PLAY speed, the rate of the smoothing clock is permanently checked. Each time the display is fast or slow by an amount of three seconds, the number 2 is respectively added to or subtracted from the contents of a special xegieter, internal to the processor, initially reset to zero at the beginning of PLAY. When the contents of this special register exceed ~3 or -4, the warning LED is switched on. Also, a flag is set and
2 is loaded in the register. Then, another checking sequence is performed and, should the special register overflow, the tape type is changed, if possible, while the register and flag are reset to zero.
Provision is made for the automatic correcting of the type of cassette not to become operative until the tape has been driven for a certain length after the cassette has been intro-duced at the start of the tape. Since the materials used to attach the magnetic tape to the reels have variable and different thicknesses from those of the magnetic tapes, they can falsify the calculations of tape position and thus having erratic effect on the calculations used during the automatic correction.
7`
,, ~.' , , .
1 ~ 6S~3B8 The limit number of the verifying coun~er, fixed at 3 in the description, can take any other value, according to the al To Rather t i g device display position might advantageously be made to flash. ~arlous y b mad by OD of skill I i t and scope of the inventi ~~ apparatus a cassette of a non-standard type (cassette used th reproduction of message which when engaged canoels th- au ~ at~c s-~rection d-vice changed during the travelling oi the tape.
.
.
. . . ..
- : .
. . . .
Provision is made for the automatic correcting of the type of cassette not to become operative until the tape has been driven for a certain length after the cassette has been intro-duced at the start of the tape. Since the materials used to attach the magnetic tape to the reels have variable and different thicknesses from those of the magnetic tapes, they can falsify the calculations of tape position and thus having erratic effect on the calculations used during the automatic correction.
7`
,, ~.' , , .
1 ~ 6S~3B8 The limit number of the verifying coun~er, fixed at 3 in the description, can take any other value, according to the al To Rather t i g device display position might advantageously be made to flash. ~arlous y b mad by OD of skill I i t and scope of the inventi ~~ apparatus a cassette of a non-standard type (cassette used th reproduction of message which when engaged canoels th- au ~ at~c s-~rection d-vice changed during the travelling oi the tape.
.
.
. . . ..
- : .
. . . .
Claims (11)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A method for automatically identifying and desig-nating that a cassette in a tape transport apparatus is of one type or of another known type, said types of cassettes having two reels carrying tape, said apparatus having drive means for the tape, said method comprising:
moving the tape of a cassette at fixed tape speeds;
generating signals representing the velocities of both reels during said tape movement;
utilizing said signals for calculating values derived from velocities of both said reels representative of the cassette in the apparatus;
comparing said calculated values with identifier values stored in memory for different types of cassettes to identify the type of cassette in the apparatus; and designating that a cassette in the apparatus is one known type or another known type according to the com-parison between said calculated values and said identifier values.
moving the tape of a cassette at fixed tape speeds;
generating signals representing the velocities of both reels during said tape movement;
utilizing said signals for calculating values derived from velocities of both said reels representative of the cassette in the apparatus;
comparing said calculated values with identifier values stored in memory for different types of cassettes to identify the type of cassette in the apparatus; and designating that a cassette in the apparatus is one known type or another known type according to the com-parison between said calculated values and said identifier values.
2. The method according to claim 1 in which tape positions are determined and values are obtained by calcu-lating the time difference between two tape positions and by comparing this difference with the real time interval sep-arating these tape positions.
3. The method according to claim l in which tape positions are determined and continuously displayed and calculated values are obtained by calculating the difference between a calculated tape position and the tape position indicated by the display at the moment at which the cal-culated position is obtained.
4. The method according to claim 2 in which a veri-fying counter during a given interval counts up the number of times the result of the comparison of tape positions does not fall within the stored reference interval, and in which the verifying counter enables a luminous or audible indicat-ing signal when its contents exceed a predetermined stored value.
5. The method according to claim 4 in which simul-taneously with the enabling of the indicating signal, the direction and magnitude of the mean result of the compari-sons with the reference value are determined, this direction and this magnitude are compared with a reference table stored in the device, and an "assumed" type of cassette is determined in accordance with the result of this comparison.
6. The method according to claim 4 in which the interval controlling the verifying counter corresponds to a , given number of calculated positions of the magnetic tape.
7. The method according to claim 5 in which the constants of the "assumed" type of cassette are used to calculate the tape position in order to confirm or to invalidate this "assumed" type of cassette.
8. The method according to any one of the claims 1 through 3 in which the process for automatically identifying the type of cassette does not start until the tape has unwound for a certain length after the cassette has been introduced at the start of the tape.
9. The method according to any one of the claims 4 through 6 in which the process for automatically identifying the type of cassette does not start until the tape has unwound for a certain length after the cassette has been introduced at the start of the tape.
10. The method according to claim 7 in which the process for automatically identifying the type of cassette does not start until the tape has unwound for a certain length after the cassette has been introduced at the start of the tape.
11. In a tape transport apparatus for cassettes hav-ing two reels carrying tape, said apparatus having drive means for the tape controllable to provide different speeds of tape movement, signal generators for producing signals representative of the velocity of both reels and controller means connected to said reel signal generators and said drive means, the improvements in said apparatus for auto-matically identifying and designating that a cassette in the apparatus is of one type or of another known type compris-ing:
means for controlling said drive means to drive said tape at fixed tape speeds;
means utilizing signals from said signal genera-tors for calculating values derived from velocities of both said reels representative of the cassette in the apparatus, means for comparing said calculated values with identifier values stored in memory for different types of cassettes to identify the type of cassette in the apparatus;
and means for designating that a cassette in the apparatus is of one known type or another known type accord-ing to the comparison between said calculated values and said identifier values.
means for controlling said drive means to drive said tape at fixed tape speeds;
means utilizing signals from said signal genera-tors for calculating values derived from velocities of both said reels representative of the cassette in the apparatus, means for comparing said calculated values with identifier values stored in memory for different types of cassettes to identify the type of cassette in the apparatus;
and means for designating that a cassette in the apparatus is of one known type or another known type accord-ing to the comparison between said calculated values and said identifier values.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| BE873,073 | 1978-12-27 | ||
| BE873073 | 1978-12-27 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1165868A true CA1165868A (en) | 1984-04-17 |
Family
ID=3861730
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000342508A Expired CA1165868A (en) | 1978-12-27 | 1979-12-21 | Method and apparatus for correcting automatically the designation of type of tape carrier |
Country Status (7)
| Country | Link |
|---|---|
| US (1) | US4357643A (en) |
| CA (1) | CA1165868A (en) |
| ES (1) | ES487308A1 (en) |
| FR (1) | FR2445575B1 (en) |
| GB (1) | GB2039127B (en) |
| IT (1) | IT1209162B (en) |
| NL (1) | NL7909146A (en) |
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| AT395301B (en) * | 1987-06-11 | 1992-11-25 | Vetter Guenther | PRESSING DEVICE |
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| KR100608597B1 (en) * | 2004-06-29 | 2006-08-03 | 삼성전자주식회사 | Method for adaptive recording in combo system |
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| JPS5951054B2 (en) * | 1977-08-25 | 1984-12-12 | ソニー株式会社 | Recording/playback device |
| JPS6012711B2 (en) * | 1977-12-29 | 1985-04-03 | ソニー株式会社 | Magnetic tape winding amount display method |
| JPS6014430B2 (en) * | 1978-05-08 | 1985-04-13 | ソニー株式会社 | Recording/playback device |
-
1979
- 1979-12-19 NL NL7909146A patent/NL7909146A/en not_active Application Discontinuation
- 1979-12-20 IT IT7928281A patent/IT1209162B/en active
- 1979-12-21 FR FR7932133A patent/FR2445575B1/en not_active Expired
- 1979-12-21 CA CA000342508A patent/CA1165868A/en not_active Expired
- 1979-12-21 US US06/105,980 patent/US4357643A/en not_active Expired - Lifetime
- 1979-12-21 GB GB7944071A patent/GB2039127B/en not_active Expired
- 1979-12-27 ES ES487308A patent/ES487308A1/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| IT7928281A0 (en) | 1979-12-20 |
| FR2445575A1 (en) | 1980-07-25 |
| NL7909146A (en) | 1980-07-01 |
| GB2039127B (en) | 1983-08-17 |
| US4357643A (en) | 1982-11-02 |
| ES487308A1 (en) | 1980-08-16 |
| FR2445575B1 (en) | 1985-10-04 |
| GB2039127A (en) | 1980-07-30 |
| IT1209162B (en) | 1989-07-10 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |